[NicolasArg]

Hello board, long time lurker, first time poster here.
I bought a taig mill a couple of years ago and a gecko 540 controller, tested it and never had the opportunity to use it properly (except for several cam program dry testing before cutting on a bigger, knee type cnc converted mill) until now.
During the first cut in Delrin at 120 mm/min, my X motor shorted, although thankfully the gecko is ok.
I managed to measure the motor temp (on all axis) during the cut and it was around 100-102ºC. I'm waiting for new motors now and decided to review the wiring.
My electronic setup is:
1). Power supply: Mean Well Nes 350 48V
2). Motors: 6 leads Fulling FL57STH76-1006A, the data sheet is attached to this post
3). Gecko G540.
I'm testing it with no limit switches or external inputs.

I wired the motors using AWG22 wire using the following diagram:
One end tap and one center tap per phase: Black A to pin 9; Yellow O to pin 8; Red B to pin 7; White M to pin 6
And soldered a 2,2K 5% 1/4W resistor to pins 1-5.
I capped off and isolated the green and blue wires.
So:
a) I'm VERY electronically challenged and would appreciate if someone could take the time to review my wiring as described above. I'd like to know if I simply had a bad motor or my wiring is wrong. Why the steppers run so hot?
b). Is my power supply enough for adding a 4th axis using the same motor?
c). I'm making an independent ground right now just for the Taig-Gecko, how should I connect the ground wire to the g540? My enclosure is aluminum.

Thanks a lot in advance and sorry for my english.

[Eldon_Joh]

you are only using half of the coil in that motor, and running it at 2.2 amps. this is not good.

better would be to use the whole coil and set the resistor to limit the current to 1 amp. (i think this is 1K, but read the gecko manual)

black and green is one coil, red and blue is the other.

the stepper motor is rated for 1 amp in unipolar mode, which means its rated for half of the coil to be passing 1 amp of current at any given time.

operating that motor at 2.2 amps in bipolar mode but using half of the coils, you are basically dumping about 4.8 times as much heat as the stepper was designed for, into half of the motor coils. this means the total amount of power, about 2.4 times as much, that's why it reached 100C.

you should be safe running the motor at 1 amp in bipolar mode, connecting the gecko to black and green, red and blue, at 1 amp.


if you really want to, you can disassemble the motor (but do not pull the rotor out of the stator) and rewire it as an 8 wire motor, then set the gecko for 2 amps.
you will not gain any torque at slow speeds,, but you will gain torque at higher rpm.

[NicolasArg]

Thank you Eldon_Joh, I just wish I've read your reply yesterday, I made a few cuts using just the x and y and bricked the Gecko G540 itself! It won't come out the fault state and I already followed the troubleshooting guide in the manual.
That's the second gecko g540 I burn with this setup. Extremely frustrating.
What puzzles me (frustrates, irritates, etc) is that initially I was going to wire the thing using just the wiring you described but decided to double check with gecko and received the following from M. Freimanis:
" Thank you for contacting Geckodrive technical support. Sorry for taking so long to get back to you.

Those motors will work just fine with the G540 in a half winding configuration. You will connect one end tap and one center tap per phase and cap off the other end tap wire. Your current rating per motor will be 2A and your inductance rating will be 3.5mH, which will work very well with that power supply"

To wich I replied: "... just found a local Mean Well dealer and they happen to have a Mean Well Nes 350 power supply. It's a 48V unit rated at 7.3A. I'll be using 3 motors, so If I'm correct, the 7.5A will be enough for the 6A my motors will demand. Is that correct?
And an additional question, since my motors will be running at 2A, I'll have to solder a 2K 5% 1/4W resistance according to the manual. Is that correct?"

And recieved the following: "
That is all correct. That power supply will work very well and the 2K resistor will limit the current to the motors so they do not overheat.

Please let me know if you have any more questions. Thank you!"

So basically that advice from gecko cost me 2 gecko g540 and 2 steppers?


Thanks again for your help.

[NicolasArg]

Just found my original mail to gecko support, an excerpt :
"As far as I can tell from the wiring diagram, the black wire goes to the pin 9, the green wire goes to the pin 8, the red wire goes to the pin 7 and the blue wire goes to the pin 6. What do I have to do with the common wires, yellow and white?
I've attached the specs of the motor in a pdf in case this could be of any help"

[Eldon_Joh]

you should not be able to brick the gecko by configuring the motor wrong. i've heard you can run it at 60 volts too, but you didn't hear that from me.


anyhow, yes you can run half the winding. you'll get more torque at higher rpm, but more heat in the motor. as i explained, at 2.2 amps you're dumping 4.8 times as much heat as it was intended to, into half the coils. so overall its 2.4 times as much heat (which explains the 100C outside surface temperature) however, internally depending on how the stepper is wired, that would be enough heat to short the coils together.
however this shouldn't blow up the gecko either. you will just loose a lot of motor torque.

just ignore the yellow and white wires if you wire it as I suggested. (tape them off of course)

[NicolasArg]

Thank you,
I actually disassembled the faulty G540 a couple of hours ago and found out that the X g250x driver is gone, so I put one from a previous board I have and at least got the green light on the unit when plugged in and connected to the E-stop.
Hopefully I'll buy some more shielded wire and 1k resistors tomorrow and will try to wire it as you suggested. Just hope the remaining motors I have are still good to go.
Thanks!

[jfong]

Per the manual, the g251 drivers are not protected from shorted windings. If the motor got hot enough, it could of shorted internally. Or the stepper may be poorly made with bad internal insulation. I wouldn't trust that motor again. You may end up destroying another driver.

[NicolasArg]

Well, I'm back from a flu. Thank you all for the info and the help.
@Eldon_Joh: I wired the motors just as you suggested and measured their temp with an infrared thermometer. They Idle at 25-35ºC now (used to idel at 60ºC) and run at about 50-65ºC. I didn't try them hard but with the former wiring after 5 or so minutes of work they'd reach 100ºC.
@jfong: I got 3 new motors in the mail yesterday and will wire them for the XYZ. Unfortunately I'm out of budget for a new 4th one so will have to use one of the old ones for the A axis. I know it's risky but hope that it will hold for indexing.
I also contacted gecko support and we are working on a solution now for the damaged units.
Thanks again to all.